The present invention relates to a method for applying a coating agent and to an electronic control unit.
An electronic control unit includes an electronic circuit board accommodated in a housing. In the prior art, various measures are taken to make the housing waterproof. For example, Japanese Laid-Open Patent Publication No. 2005-150633 describes an electronic control unit having a waterproof structure. In a vehicle, space is limited. It is thus important that space be effectively used. Therefore, to increase the mounting freedom of an electronic control unit in a vehicle, the electronic control unit must have higher water resistance. Accordingly, in an electronic control unit having a waterproof structure, it is desirable that the electronic circuit board be coated with an anti-moisture agent.
However, in cases in which there are locations that must undergo soldering after the electronic circuit board is mounted on the housing, the anti-moisture agent may hinder soldering. Thus, in the prior art, the soldered locations are masked before immersing the electronic circuit board in a coating agent (anti-moisture agent). Alternatively, after mounting the electronic circuit boards to the housing, the anti-moisture agent is coated on the electronic circuit board with a brush. However, such masking or coating is troublesome. Further, depending on how the electronic circuit board is accommodated in the housing, some portions of the electronic circuit board may be left uncoated by the anti-moisture agent. Accordingly, improvements must be made to the application of a coating agent.